Fuel injectors or solenoid operated injection valves perform the function of supplying fuel into the cylinders of internal combustion engines or adjacent to the intake valves of the cylinders of internal combustion engines. Depending on the characteristics of the engine, the fuel injector discharges its fuel in a pencil stream, a cone shaped spray, dual sprays, etc. all with or without the fuel having a toroidal or tangential or swirl motion applied thereto.
U.S. Pat. No. 4,971,254, ('254) issued on Nov. 20, 1990 to Daly et al and entitled "Thin Orifice Swirl Injector Nozzle" is illustrative of a fuel injector wherein the fuel is passed through a guide member upstream of a thin orifice member by a plurality of holes that are spaced radially outwardly from the axis of the guide member. As the fuel passes through these holes, the fuel acquires angular momentum which increases the divergence of the column of fuel that is emitted from the thin disc orifice member.
In this patent, '254, the guide member is stationary and rests on the conical seat member of the injector. When the needle is in its closed position, a small amount of residual fuel remains between the bottom of the guide member and the inlet of the seat member. When the needle is opened this small amount of residual fuel is dumped and only the subsequent fuel, the fuel passing through the guide member, will begin to exit the injector in a swirling manner.